In a wire-cut electric discharge machine arranged to effect electric discharge machining by producing electric discharge between a workpiece and a wire electrode (hereinafter referred to as wire), generally, the wire is supported and guided on a predetermined wire traveling path by the use of upper and lower guides which are respectively disposed above and below the workpiece, and at the same time, a working fluid is supplied between the workpiece and the wire from a nozzle hole formed in a nozzle which is attached to a housing of each guide integrally therewith so as to cool the wire and eliminate chips resulting from machining. Conventionally, in order to support the wire on the predetermined wire traveling path in a stable manner, a guide of a type having a V-shaped stationary piece (or a V-shaped groove) and a movable piece arranged to be pressed by an operating member of an actuator toward the stationary piece is employed for three-point supporting the wire by the movable and stationary pieces.
However, in the three-point support guide of the above-mentioned kind, a highly pressurized working fluid filled between the housing and the nozzle can penetrate into the interior of the actuator and act upon the operating member of the actuator so as to cause the operating member to be displaced from its predetermined wire support position in the direction away from the stationary piece. In this case, the actuator cannot apply a predetermined urging force on the wire via the movable piece of the three-point support guide, so that the wire cannot be accurately supported on the predetermined wire traveling path.